[#43120] [ruby-trunk - Bug #6124][Open] What is the purpose of "fake" gems in Ruby — Vit Ondruch <v.ondruch@...>

27 messages 2012/03/07

[#43142] Questions about thread performance (with benchmark included) — Rodrigo Rosenfeld Rosas <rr.rosas@...>

A while ago I've written an article entitled "How Nokogiri and JRuby

10 messages 2012/03/08

[#43148] [ruby-trunk - Feature #6126][Open] Introduce yes/no constants aliases for true/false — Egor Homakov <homakov@...>

16 messages 2012/03/09

[#43238] [ruby-trunk - Feature #6130][Open] inspect using to_s is pain — Thomas Sawyer <transfire@...>

21 messages 2012/03/11

[#43313] [ruby-trunk - Feature #6150][Open] add Enumerable#grep_v — Suraj Kurapati <sunaku@...>

17 messages 2012/03/15

[#43325] [ruby-trunk - Bug #6154][Open] Eliminate extending WaitReadable/Writable at runtime — Charles Nutter <headius@...>

25 messages 2012/03/16

[#43334] [ruby-trunk - Bug #6155][Open] Enumerable::Lazy#flat_map raises an exception when an element does not respond to #each — Dan Kubb <dan.kubb@...>

9 messages 2012/03/16

[#43370] [ruby-trunk - Feature #6166][Open] Enumerator::Lazy#pinch — Thomas Sawyer <transfire@...>

15 messages 2012/03/17

[#43373] [ruby-trunk - Bug #6168][Open] Segfault in OpenSSL bindings — Nguma Abojo <git.email.address@...>

14 messages 2012/03/17

[#43454] [ruby-trunk - Bug #6174][Open] Fix collision of ConditionVariable#wait timeout and #signal (+ other cosmetic changes) — "funny_falcon (Yura Sokolov)" <funny.falcon@...>

10 messages 2012/03/18

[#43497] [ruby-trunk - Bug #6179][Open] File::pos broken in Windows 1.9.3p125 — "jmthomas (Jason Thomas)" <jmthomas@...>

24 messages 2012/03/20

[#43502] [ruby-trunk - Feature #6180][Open] to_b for converting objects to a boolean value — "AaronLasseigne (Aaron Lasseigne)" <aaron.lasseigne@...>

17 messages 2012/03/20

[#43529] [ruby-trunk - Bug #6183][Open] Enumerator::Lazy performance issue — "gregolsen (Innokenty Mikhailov)" <anotheroneman@...>

36 messages 2012/03/21

[#43543] [ruby-trunk - Bug #6184][Open] [BUG] Segmentation fault ruby 1.9.3p165 (2012-03-18 revision 35078) [x86_64-darwin11.3.0] — "Gebor (Pierre-Henry Frohring)" <frohring.pierrehenry@...>

8 messages 2012/03/21

[#43672] [ruby-trunk - Feature #6201][Open] do_something then return :special_case (include "then" operator) — "rosenfeld (Rodrigo Rosenfeld Rosas)" <rr.rosas@...>

12 messages 2012/03/26

[#43678] [ruby-trunk - Bug #6203][Open] Array#values_at does not handle ranges with end index past the end of the array — "ferrous26 (Mark Rada)" <markrada26@...>

15 messages 2012/03/26

[#43794] [ruby-trunk - Feature #6216][Open] SystemStackError backtraces should not be reduced to one line — "postmodern (Hal Brodigan)" <postmodern.mod3@...>

15 messages 2012/03/28

[#43814] [ruby-trunk - Feature #6219][Open] Return value of Hash#store — "MartinBosslet (Martin Bosslet)" <Martin.Bosslet@...>

20 messages 2012/03/28

[#43858] [ruby-trunk - Feature #6222][Open] Use ++ to connect statements — "gcao (Guoliang Cao)" <gcao99@...>

12 messages 2012/03/29

[#43904] [ruby-trunk - Feature #6225][Open] Hash#+ — "trans (Thomas Sawyer)" <transfire@...>

36 messages 2012/03/29

[#43951] [ruby-trunk - Bug #6228][Open] [mingw] Errno::EBADF in ruby/test_io.rb on ruby_1_9_3 — "jonforums (Jon Forums)" <redmine@...>

28 messages 2012/03/30

[#43996] [ruby-trunk - Bug #6236][Open] WEBrick::HTTPServer swallows Exception — "regularfry (Alex Young)" <alex@...>

13 messages 2012/03/31

[ruby-core:43817] [ruby-trunk - Feature #5741] Secure Erasure of Passwords

From: "nobu (Nobuyoshi Nakada)" <nobu@...>
Date: 2012-03-28 21:38:59 UTC
List: ruby-core #43817
Issue #5741 has been updated by nobu (Nobuyoshi Nakada).


What kind of methods will be needed for "Secure Password", do you think?
Is there any reason that it has to be real String instance?

For example, I guess it should be BINARY or US-ASCII always, so shouldn't have encode method.
sub string of it makes no sense, so no [], slice, and etc.
sub, tr, upcase, et al too.
Of course, to_sym must be prohibited as it makes the string permanent.
----------------------------------------
Feature #5741: Secure Erasure of Passwords
https://bugs.ruby-lang.org/issues/5741#change-25321

Author: MartinBosslet (Martin Bosslet)
Status: Assigned
Priority: Normal
Assignee: matz (Yukihiro Matsumoto)
Category: 
Target version: 2.0.0


In other languages it is considered good practice to securely erase 
passwords immediately after they were used. Imagine authentication
in a web app - ultimately a String containing the password arrives
at the server, where it will be processed and compared to some 
previously stored value. After this is done, there is no need to
store these password Strings any longer, so they should be
discarded right away (more on why later).

In C, you would simply overwrite the array of bytes with zeroes or
random values. In Java, Strings are immutable, that's why there it
is common practice to use char[] for all things password and overwrite
them when done.

Currently, there is no way in Ruby to overwrite the memory that
was used by a String. String#clear and String#replace both use
str_discard internally, which only frees the underlying pointer 
without overwriting it.

The problem with not erasing passwords is this: the contents of the
String stay in memory until they are finally GC'ed. But even then
only the pointer will be freed, leaving the contents mostly intact
until the memory is reclaimed and overwritten later on.

This could be exploited if an attacker had access to the memory of
the server. This could happen in many ways: a core dump after a
crash, access to the host if the server runs in a VM, or even by
deep-freezing the DRAM :) [1]

It could be argued that given the examples above, much more 
devastating attacks would be possible since in all of those
cases you more or less have physical access to the machine. But
I would still consider this to be a valid concern, if not only
for the reason of never opening additional attack surfaces if
they can be avoided relatively easily.

I also found [2], which seems to show that Python deals with 
similar problems and it also contains more background info.

Eric Hodel and I discussed this yesterday and Eric came up with
a C extension that can be used to illustrate the problem (attached).

If you inspect the resulting core dump, you will find the following:

- the untouched String remains in memory fully intact
- the String#clear'ed String remains to a large extent, typically the
  first character is missing - so if you typed "PASSWORD", search for
  "ASSWORD" (unintentional pun) instead
- The String#clear_secure'ed will have been completely erased, no 
  traces remain

My questions:

1. Would you agree that we need this functionality?
2. Where would we ideally place it? I'm not sure whether
   String is the perfect place, but on the other hand, String
   is the only place where we have access to the implementation
   details.
3. Are there better alternative ways how we could achieve this?

[1] http://www.schneier.com/blog/archives/2008/02/cold_boot_attac.html
[2] http://stackoverflow.com/questions/728164/securely-erasing-password-in-memory-python


-- 
http://bugs.ruby-lang.org/

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